[cmake] Also pass CMAKE_ASM_COMPILER_ID to next stage when bootstrapping

[hintonda]

Summary

If CMAKE_ASM_COMPILER is set, cmake assumes
CMAKE_ASM_COMPILER_ID was also set, and doesn't try to set it.

Without CMAKE_ASM_COMPILER_ID, cmake can't set
CMAKE_ASM_COMPILER_OPTIONS_TARGET either, which means
CMAKE_ASM_COMPILER_TARGET is ignored, causing cross compiling to fail,
i.e., --target=${CMAKE_ASM_COMPILER_TARGET} isn't passed.

[compnerd]

Took a bit of reading to realize that the compiler is being set to clang, and therefore CMAKE_ASM_COMPILER_ID should be Clang.

[hintonda]

In D42232#982043, @compnerd wrote:

Took a bit of reading to realize that the compiler is being set to clang, and therefore CMAKE_ASM_COMPILER_ID should be Clang.

Thanks, I'll add that to the commit message.

cfe/trunk/CMakeLists.txt

if (CLANG_ENABLE_BOOTSTRAP)
   if(WIN32)
     set(C_COMPILER "clang-cl.exe")
     set(CXX_COMPILER "clang-cl.exe")
   endif()
 
   set(COMPILER_OPTIONS
     -DCMAKE_CXX_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/${CXX_COMPILER}
     -DCMAKE_C_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/${C_COMPILER}
-    -DCMAKE_ASM_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/${C_COMPILER})
+    -DCMAKE_ASM_COMPILER=${LLVM_RUNTIME_OUTPUT_INTDIR}/${C_COMPILER}
+    -DCMAKE_ASM_COMPILER_ID=Clang)
 
   if(BOOTSTRAP_LLVM_BUILD_INSTRUMENTED)
     add_dependencies(clang-bootstrap-deps llvm-profdata)
     set(PGO_OPT -DLLVM_PROFDATA=${LLVM_RUNTIME_OUTPUT_INTDIR}/llvm-profdata)
   endif()
 
   if(LLVM_BUILD_INSTRUMENTED)
     add_dependencies(clang-bootstrap-deps generate-profdata)